The present invention relates to an arrangement for heating an intake pipe of a spark-ignited internal combustion engine, in which electrical heater elements (PTC-elements) with positive temperature coefficients are located in a housing.
The purpose of such an arrangement is to evaporate the fuel precipitated on the wall of the intake pipe by intensive heating, in order to achieve good mixture processing while the engine is still cold.
Upon reaching the operating temperature of the engine, the abnormal temperature of the PTC elements is reached, causing the resistance of the PTC elements to rise so rapidly that the heating device virtually requires no energy from the battery.
With a known arrangement, the heating current is delivered to the PTC elements via press-on or contact springs. This type of contact during use leads to difficulties due to vibrations since the components are not fixed relative to each other and in relation to the heating surface.
It is an object of the present invention to provide an arrangement where elements are safely supplied with current and are secured against shifting due to vibration.
Another object of the present invention is to provide an arrangement of the foregoing character which is substantially simple in construction and may be economically fabricated.
A further object of the present invention is to provide an arrangement for heating the intake pipe, as described, which may be readily maintained in service and which has a substantially long operating life.